It would be surprising if they didn’t have an idea that this would happen given that even US agencies now claim to have been expecting it. One possibility is that it was allowed to happen in order to ferret out people who would support the coup. Prigozhin was likely let go in order to get the wagner troops to stand down, they figured they’d rather avoid bloodshed than go after him right now.
Meanwhile, CIA has bungled plenty of coups in its time. They couldn’t even get a coup in Belarus going, what chance would they have in Russia.